1. Field of the Invention
This invention relates to tool holder assemblies for use in machine tools which perform various types of opertions, such as milling, drilling, boring, tapping, and the like. The invention is particularly concerned with a tool holder assembly of the type wherein a tool holder or chuck is secured to a rotary spindle by a draw bar which functions to draw a tool holder into a tight frictional engagement with a seal formed in the spindle, and whereby the tool holder and the tool mounted thereon rotates with the spindle.
2. Description of the prior art
It is known in the machine tool art to provide tool holders or chucks which in turn are releasably mounted in a rotary spindle. The tool holder generally has a conical, or frusto-conical shank or body portion that is seated in a conical, or frusto-conical socket or recess formed in the rotary spindle. The tool holder is held in position by a draw bar and a tool holder gripping means, such as a collet means. The draw bar is axially movable with respect to the spindle, and when the draw bar is moved inwardly of the spindle, the collet means engages the tool holder and holds the tool holder in tight frictional engagement with the socket formed in the spindle so that the tool holder and the tool carried thereon rotates with the spindle. An example of the last described tool holder assembly is illustrated in U.S. Pat. No. 3,868,886.